With increasing development and advance of electronic industries, a variety of electronic devices with different functions are introduced into the market. These electronic devices can meet different requirements and gradually become essential in our daily lives.
During normal operations, the electronic device has to receive a corresponding voltage. Consequently, the electronic device is electrically connected with a power conversion device for receiving the desired voltage. For example, the power conversion device receives an input voltage from a battery, a utility power source or a regeneration power source and converts the input voltage into an output voltage. When the electronic device is electrically connected with the power conversion device, the output voltage is outputted from the power conversion device to the electronic device.
The power conversion device comprises a switching converter. In addition, the switching converter comprises at least one switch element. The switching converter receives the input voltage. By alternately turning on and turning off the switch element, the switching converter may convert the input voltage into an output voltage. When a connector (e.g. a plug or a USB connector) of an electronic device is connected to the power conversion device, the output voltage is provided to the electronic device. Consequently, the electronic device can be normally operated.
However, the conventional power conversion device still has some drawbacks. For example, if no electronic device is electrically connected to the power conversion device when the power conversion device receives the input voltage, the switching action of the switch element of the switching converter is continuously performed to generate the output voltage. Due to the switching loss of the switch element, the conventional power conversion device continuously consumes the energy of the input voltage. In case that the electrical quantity of the power source is limited (e.g. a battery), the problem of the switching loss is more evident.
Nowadays, some mechanisms are provided for solving the above problems. In accordance with an approach, the connector of the electronic device (i.e. a load) is additionally equipped with a detecting pin. When the connector of the load is connected with the power conversion device, the detecting pin of the connector generates a detecting signal. After the detecting signal is received by the power conversion device, the switching action of the switching element of the switching converter is enabled. Consequently, the undesired energy loss can be reduced. Since the connector of the load is designed according to the known specifications, the additional detecting pin may increase the fabricating cost.
In accordance with another approach, the conventional power conversion device is equipped with an external switch for controlling the operation of the switching element of the switching converter. When the connector of the load is connected with the power conversion device, the external switch is turned on by the user, and thus the switching action of the switching element of the switching converter is performed. When the connector of the load is disconnected from the power conversion device, the external switch is turned off by the user, and thus the switching action of the switching element of the switching converter is stopped. Consequently, the undesired energy loss is reduced. Since the external switch is controlled by the user according to the result of judging whether the connector of the load is connected with or disconnected from the power conversion device, this controlling method is not user-friendly. If the user forgets to disable the external switch when the connector of the load is disconnected from the power conversion device, the switching action of the switching element of the switching converter is continuously performed. Under this circumstance, the problem of generating the switching loss still occurs.
Therefore, there is a need of providing a power conversion device and a controlling method in order to overcome the above drawbacks.